In recent years, wireless communications have become increasingly important in a number of vehicle control systems. Remote vehicle entry transmitters/receivers, for example, are used for locking and unlocking a vehicle door, unlatching a trunk latch, or activating or deactivating an alarm system equipped on the vehicle. This remote entry device is commonly referred to a remote keyless entry (RKE) fob. The RKE fob is typically a small rectangular or oval plastic housing with a plurality of depressible buttons for activating each one of the wireless operations. The RKE fob is carried with the operator of a vehicle and can wirelessly perform these functions when within a predetermined reception range of the vehicle. The RKE fob communicates with an electronic control module within the vehicle via a RF communication signal.
Other communication modules may be provided within the vehicle system. These can include, for example, a tire pressure monitoring (TPM) system. A TPM system disposes pressure sensors on or within vehicle tires to sense the pressure within a respective tire and report low or high pressure conditions to a driver. TPM systems sense tire pressure within a tire and transmit a signal to a body-mounted receiving unit located external to the tire for processing tire pressure data. Interference may occur when the signal transmitted by the transmitting devices of TPM system is broadcast in the same operating frequency of the RKE receiver.
Even more recently, complex embedded electronic systems have become common to provide access and start functions, and to provide wide ranging functions to improve driver safety and convenience. These systems include Passive Entry and Passive Start (PEPS) systems. In PEPS systems, a remote receiver and transmitter (or transceiver) is carried with the user in a portable communication device such as a key fob or a card. The portable communication device when successfully challenged transmits a radio frequency (RF) signal to a module within the vehicle for performing a variety of remote vehicle function such door lock/unlock, enabling engine start, or activating external/internal lighting. Passive entry systems include a transmitter and receiver (or transceiver) in an electronic control module disposed within the vehicle. The transceiver is typically in communication with one or more devices (e.g., door lock mechanism) for determining when a request for actuation of a device is initiated (e.g., lifting a door handle) by a user.
Upon sensing the request for actuation, the transceiver broadcasts a passive entry interrogating signal. The fob upon receiving the interrogating signal from the ECU, the portable communication device determines if the interrogating signal is valid. If it is determined a valid signal, then the fob automatically broadcasts an output signal which includes an encrypted or rolling identification code to the electronic control module. The electronic module thereafter determines the validity of the output signal and generates a signal to the device to perform an operation (e.g., the door lock mechanism to unlock the door) if the output signal is determined valid.
As the number of wireless communication systems and number of wireless controls has increased, it has become increasingly important to assure that communications are fast and efficient. Thus, there exists a need for improved communications systems that can quickly transmit and process wireless communications packets.